This invention relates to an improved catalyst and adsorbent composition for removal of sulfur dioxide from waste gases, such as gases containing not over 10% by volume of sulfur dioxide, said catalyst/adsorbent being composed of activated carbon with a vanadium compound supported thereon. More particularly, the invention relates to improvments of such catalyst/adsorbent by promotion thereof by use of a nickel compound, a potassium compound, or preferably mixtures thereof.
Use of a catalyst/adsorbent of sulfur dioxide, composed of activated carbon and a vanadium compound supported thereon is known, e.g. from U.S. Pat. No. 3,667,910 of June 6, 1972 to Y. Eguchi. Moreover the further activation of such activated carbon/vanadium compound adsorbent is shown in German patent publication DOS 2253536 published May 24, 1973, wherein use of a phosphorus compound and/or tin compound and/or boron compound together with the vanadium and the activated carbon support is proposed.
The subject adsorption of sulfur dioxide is taught in the prior art as involving oxidation of the sulfur dioxide to sulfur trioxide, which in the presence of water is converted to sulfuric acid. The waste gases containing less than 10% by volume of sulfur dioxide, to which such processes are applicable, generally contain sufficient oxygen for the requisite oxidation of sulfur dioxide; or if not, the oxygen can be added as oxygen of air or otherwise. Usually, also, water is present in such gases and presence of water is desirable in such adsorption process.